This invention relates to a method and device for tissue removal, especially for surgical treatment of the uterus or prostate.
Electrocautery has been in use for many years as a general surgical tool, such as for trans-cervical fibroid removal. The uterus is first flooded under pressure with a nonconductive fluid, such as sorbitol-mannitol fluid or the like under sufficient pressure to separate the walls of the uterus and render the surgical site suitable for optical fiber observation. This procedure is generally described as uterine cavity distension. During this flooding, an electrocautery surgical tool is inserted into the uterus through the cervix. Electrical current at high voltage settings (typically an alternating current about 750 KHz and 2000-9000 volts) is transmitted from a cutting surface of the surgical instrument to the surgical site. The cutting surface usually consists of a wire or solid shape. The transmission of current to the uterus is monopolar, and the circuit is completed by a conductive path to the power unit through a conductive pad applied to the patient's skin.
The electrical current is concentrated at the cutting surface. Heat generated from the resistance of tissue to the flow of electrical current is high enough to vaporize cells near the cutting surface. Thus, a cut is made with very little physical resistance to the cutting motion. Heat from the cut cauterizes small blood vessels so that visibility and control remain good.
During uterine cavity distension, the same electrical resistance heating may be used at lower power settings to cauterize bleeding tissue and to kill selected areas of the tissue through ablation. Such cautery electrodes can be larger in area so as to treat broader surfaces. Cautery is used in gynecology to ablate the endometrial lining of the uterus. This procedure is often performed using a conductive roller similar in shape to a football which heats a wide swath of tissue along the inner surface of the uterus.
Electrocautery tools are compact and require a minimum of area in which to work. Since the tool only cuts when the power is turned on, it can be safely maneuvered into small areas. Electrocautery has found broad general application in the treatment of enlarged prostate glands and in the removal of uterine fibroids.
A secondary effect of the removal of tissue, particularly in the areas of prostate reduction and fibroid removal, is that separated tissue fragments typically remain in the working area and must be periodically flushed or suctioned away to preserve the required visibility necessary for surgery. The clean, well-controlled action of electrocautery is now slowed by this need to remove fragments which obstruct visibility. Therefore, the requirement for intermittent clearing of the surgical site prolongs fibroid removal and other electrosurgical procedures.
It is known that ultrasound can add significant value to tissue resection and ablation procedures. Using high-frequency ultrasound, anatomical landmarks and tissue features can be imaged in depth, which cannot be done by optical instruments. Depth information provides improved guidance and monitoring capabilities. It enables the surgeon to monitor the progress of tissue treatment, and thereby lessens the risk of complications. In addition, the improved visualization provided by ultrasound can help to shorten procedure times.
At the present time as for example during uterine cavity distention, it is not practical to introduce ultrasound probes without considerable complication.
To perform ultrasound measurements during electrocautery, the surgical probes for the electrocautery procedure must first be removed and thereafter, ultrasound introduced. Finally, and after such measurements, surgery can resume with reintroduction of the surgical probes. With such procedures, the surgeon has difficulty returning to the original surgical site. For this reason, ultrasound is not usually utilized for measurement of uterine wall thickness by an intrauterine transducer.